From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 9D5E689C for ; Wed, 3 Aug 2016 18:00:25 +0000 (UTC) Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 42AA62D1 for ; Wed, 3 Aug 2016 18:00:25 +0000 (UTC) Date: Wed, 3 Aug 2016 21:00:21 +0300 From: "Michael S. Tsirkin" To: Andy Lutomirski Message-ID: <20160803203018-mutt-send-email-mst@kernel.org> References: <27174.1470221030@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Cc: Josh Boyer , Jason Cooper , "ksummit-discuss@lists.linuxfoundation.org" , James Bottomley , Mark Brown Subject: Re: [Ksummit-discuss] [TOPIC] Secure/verified boot and roots of trust List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, Aug 03, 2016 at 10:23:00AM -0700, Andy Lutomirski wrote: > >>> I don't see a compelling argument for why we'd want to do module hashing at > >>> all, given that we have to have the signature checking mechanism around anyway > >>> for various reasons. > >> > >> I think that, for the Secure Boot usecase, we actually wouldn't need > >> the signature checking mechanism at all. Firmware signature checking > >> in-kernel is important for some chain-of-trust use cases but AFAIK not > >> for Secure Boot for standard desktop distros. > > > > Without an IOMMU you can probably subvert any DMA capable device that > > loads unsigned firmware, at which point you're in a bad place again. > > This isn't something I'm losing much sleep over, since attacks that > > only work if you have a specific piece of hardware installed are much > > less exciting. We'd still need signature checking so that users can > > install their own signing keys, and I don't see distributions being > > terribly enthusiastic about having two unrelated module validation > > systems. > > That's a question for the distros. My intent would be to make the > module hashing scheme as painless as possible for the distros: distros > would just enable a config option and, if needed, adjust their debug > info generation slightly. It's actually nice not having to rebuild the kernel each time though. Can the hash-checking code itself be a module (LSM?), such that hash isn't checked if it's not loaded? One could imagine loading that e.g. from the initrd. > _______________________________________________ > Ksummit-discuss mailing list > Ksummit-discuss@lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/ksummit-discuss